There have been developed a variety of cooling units that cool a heat generating part such as a central processing unit (CPU) in an electronic apparatus, for example, a server. For example, there has been developed a cooling unit that circulates cooling liquid in a circulation channel using a pump. The cooling liquid or coolant absorbs heat generated by heat generating parts through cooling jackets mounted on the heat generating parts and dissipates the heat through a radiator. In this manner, the cooling unit cools the cooling fluid.
In addition, there has been developed a coolant distributor that allows coolant to flow into a flow channel from an inlet pipe on one side and flow out of an outlet pipe on the other side, refer to, for example, International Publication Pamphlet No. WO 99/46544. In the coolant distributor, the width of the flow channel gradually expands from the inlet pipe to the outlet pipe.
FIG. 1 illustrates an existing radiator 100. The existing radiator 100 includes a tank 110 having a supply chamber and a collection chamber (neither is illustrated) partitioned in the internal space and a loop channel tube 120 having an internal coolant channel therein. As illustrated in FIG. 1, the loop channel tube 120 of the existing radiator 100 is flat in shape. Four channel tubes 120 are provided on each of both sides of the tank 110. That is, eight channel tubes 120 are joined to the tank 110 in total. Each of the channel tubes 120 includes a pair of counterflow channel units 122 that face each other with a folded portion 121 therebetween. In the folded portion 121, the channel tube 120 is folded in a U shape. A corrugated fin 123, which is a corrugated plate, is fusion-bonded between the two counterflow channel units 122 that face each other.
In addition, the tank 110 includes an inlet nozzle 111 that communicates with a collection chamber formed therein and an ejection nozzle 112 that communicates a supply chamber formed therein. A hose (not illustrated) for transporting coolant is attached to each of the inlet nozzle 111 and the ejection nozzle 112. The counterflow channel units 122 of the channel tube 120 are disposed so as to face each other. The corrugated fin 123, which is a corrugated plate, is fixed between the two counterflow channel units 122.
In general, the channel tube 120 is connected to the tank 110 by brazing. As illustrated in FIG. 1, an insertion port 113 having a slit shape is formed in a side surface of the tank 110. The insertion port 113 allows both the ends of the channel tube 120 to be inserted thereinto. The end of one of the counterflow channel units 122 is inserted into the supply chamber of the tank 110, and the end of the other counterflow channel unit 122 is inserted into the collection chamber of the tank 110. Thereafter, the channel tube 120 is connected to the tank 110 by brazing.
The coolant of the radiator 100 flows into the tank 110 through the inlet nozzle 111. Thereafter, the coolant flows from the collection chamber of the tank 110 to the ejection nozzle 112 via the channel tube 120 and the supply chamber of the tank 110. When the coolant flows in the internal channel of the channel tube 120, the heat of the coolant dissipates from the corrugated fin 123. In this manner, the coolant is cooled. Note that such a cooling unit has a blower fan that sends air to the radiator. Thus, dissipation of heat from the corrugated fin 123 is facilitated by the air sent from the blower fan.